Reference was made in our previous paper to the dearth of published information on the chemical composition of hay as fed to stock in Wales (]). The data obtained as a result of the present survey were compared with the results of investigations in other parts of the British Isles. This paper deals with the ash constituents, and all samples of Welsh hay were analyzed for total and soluble (silica-free), ash, calcium, phosphorus and chlorine. Magnesium and certain trace elements were also determined in a large number of samples. Comparison is again made with results obtained at other centres and is concerned mainly with major elements, for some investigators include figures for total ash, others give figures for major ash constituents as well, hut the information available on trace elements in hay is very restricted. MAJOR MINERALS Analytical methodsTotal ash was determined by igniting 5 grm. of material in an electric muffle furnace at 5OO'-6OO' ' C to a light grey ash. Silica was determined in the ash in the usual manner, and total ash -silica = HCl soluble or silica-free ash. Calcium was precipitated from the HCl extract as oxalate and determined volumetrically by titration with potassium permanganate. The well-known PIIMBIIRTON method was used to determine phosphate, while the method used to determine chloride was based on DAVIES' wet-oxidation method (16). Magnesium was determined gravimetrically as pyrophosphate. The resultsAll data obtained in this investigation are expressed on a Dry Matter basis. Tbe mean values for the content of major minerals in the difFerent types of bay, together witb their standard deviations and range of values are given in Table 1. TOTAL ASHThe meadow hays bave tlie higher mean ash content. Maximum vahies are of tbe same order for the meadow and seeds bays, but the latter attain lower minima. There is little difference in tbe average asb contents of tbe 1st, 2nd and 3rd year seeds due, in all probability, to tbe preponderance of stemmy ryegrass and low content of clover. This was similarly reflected in tbe crude protein content. A study of the distribution of asb in the samples furtber emphasizes the differences between the meadow and seeds hays. Twenty-nine per cent of the former but only 12 per cent of tbe latter contain over 7-0 per cent of asb, whereas 52 per cent of tbe seeds compared with 35 per cent of tbe meadow hays contain less tban 6 per cent. Seventy-five per cent of all samples contain hetween 5 and 7 per cent.